Pathophysiology of Intracranial Aneurysms: COX-2 Expression, Iron Deposition in Aneurysm Wall, and Correlation With Magnetic Resonance Imaging.

BACKGROUND AND PURPOSE

The pathophysiology of development, growth, and rupture of intracranial aneurysms (IAs) is only partly understood. Cyclooxygenase 2 (COX-2) converts arachidonic acid to prostaglandin H

METHODS

The study group comprised 40 patients with partly thrombosed saccular IAs. The cohort included 17 ruptured- and 24 unruptured IAs, which had all been treated microsurgically. Formaldehyde-fixed paraffin-embedded samples were immunohistochemically stained with a monoclonal antibody against COX-2 (Dako, Santa Clara, CA; Clone: CX-294). We correlated Perls Prussian blue staining, MRI, and clinical data with immunohistochemistry, analyzed using the Trainable Weka Segmentation algorithm.

RESULTS

Aneurysm dome size ranged between 2 and 67 mm. The proportion of COX-2 positive cells ranged between 3.54% to 85.09%. An upregulated COX-2 expression correlated with increasing IA dome size (

CONCLUSIONS

Iron deposition and COX-2 expression in IAs walls correlate with signal hypointensity in MRI, which might, therefore, serve as a biomarker for IA instability. Furthermore, as COX-2 was also expressed in small unruptured IAs, it could be a potential target for specific medical treatment.